Nearby
78. dust clouds in
the Milky Way
The yearly ritual of spring cleaning clears a house of dust as well as dust “bunnies”, those pesky dust balls
that frolic under beds and behind furniture. Hubble has photographed similar dense knots of dust and gas
in our Milky Way Galaxy. This cosmic dust, however, is not a nuisance. It is a concentration of elements that
are responsible for the formation of stars in our galaxy and throughout the universe.
These opaque, dark knots of gas and dust are called Bok globules, and they are absorbing light in the
center of the nearby emission nebula and star-forming region, NGC 281. The globules are named after
astronomer Bart Bok, who proposed their existence in the 1940’s.
Credit: NASA, ESA, and The Hubble Heritage Team STScI/AURA)
“Another critical discovery enabled by Hubble is the indirect discovery of an
abundant population of small, roughly 1 km diameter Kuiper Belt objects*. By
virtue of their small sizes, KBOs smaller than ~10 km in diameter are too faint to
be observed directly, even by the HST. Remarkably however, a pair of objects
smaller than 1 km diameter have been observed by the Fine Guidance Sensors,
detectors whose main purpose is to keep Hubble locked on the stars. Those
sensors detected the shadows cast by the small Kuiper Belt objects as they
passed in front of the stars Hubble was observing. While astronomers are still
trying to understand the full significance of this discovery, it appears that these
small bodies are the fragments produced during a state of significant collisional
bombardment, a process that may have been partially responsible for the
failure of the Kuiper Belt to form another full planet.
“With its unique imaging capabilities, Hubble has enabled countless discoveries
about the Kuiper Belt and the outer Solar System. The images it has taken
of Pluto’s surface and satellite family are just a sample of the iconic images
captured in NASA’s top 100 images produced by the Hubble Space Telescope.
No other [\